fast battery drain in disabled mode

[wassfila]

disabled : after factory reset, when no network was joined (no response obtained for "Discovery Request")

in this mode the Tag consumes an average of 6mA so drain the battery very fast

Solutions

• figure out a low power config for openthread stack
• application workaround to disable the stack and sleep

Although this mode never happens in normal operations, it is not without risk that by accident the users creates a factory reset condition without having an active commissioner, that's when this issue happens.